Well this is the start of a new fic and getting more crack-pot ideas out there. I have other ideas in other areas of this site. If you want to take them on, please let me know. Obviously, I do not own the Avengers or Marvel. That belongs to the great empire of the mouse.
This is very much an Avengers AU. Howard Stark is a known womanizer, what if one of his exes went crazy and kidnapped little Tony and raised him as her own. This woman could have raised him to believe that Howard was a monster and they lived their lives to oppose him. When the old Stark died, things started to change for Tony and his "mother". In the time of the first Iron Man and on to Civil War.
*Tony will still be a genius, just poor and a lot of his tech is made with limited resources.
*The mom could be part of or running an organization of special people who oppose SHEILD and most governments. Seeing SHEILD and anything like it as just another HYDRA, so Winter Soilder would be a major conflict point. Later on she could start to want to start a war with them.
*Tony may have become a teacher instead of a weapon designer. He could help these special people if they come in his sights.
*There would be a twist into how he became an Avenger, Tony would not trust Steve since Howard made the super soilder. How that can change will diepend on where you think this story should go.
*No objection to Tony having his own team, with lesser known characters. Could be frienemies with the Avengers at first but will warm up later.
I know this is not the most original idea, but it was in my head for a while. I don't know if there will be more but this is it for now.